HR: 09:15h
AN: B51E-06    [Abstracts]
TI: Natural Variation in the Carbon Oxidation State and Oxidative Ratio of a Deciduous Forest
AU: * Masiello, C A
EM: masiello@rice.edu
AF: Rice University department of Earth Science, 6100 Main St, MS 126, Houston, TX 77005, United States
AU: Calligan, L J
EM: lcalligan@yahoo.com
AF: Texas Southern University, 3100 Cleburne St, Houston, TX 77004, United States
AU: Gallagher, M E
EM: megirish@rice.edu
AF: Rice University department of Earth Science, 6100 Main St, MS 126, Houston, TX 77005, United States
AU: Hockaday, W C
EM: wch2@rice.edu
AF: Rice University department of Earth Science, 6100 Main St, MS 126, Houston, TX 77005, United States
AU: Robertson, G P
EM: robertson@kbs.msu.edu
AF: Kellogg Biological Station, Michigan State University, 3700 E. Gull Lake Dr., Hickory Corners, MI 49060, United States
AB: Here we report natural variability in the oxidative ratio (OR) and carbon oxidation state (C_ox) of a temperate, deciduous forest measured on an annual basis via elemental analysis of leaf litter. The OR of the terrestrial biosphere is a key component in O₂ -based calculations of the biosphere's uptake of fossil fuel CO₂ (eg [ Keeling, et al., 1996]). Ecosystem OR has been assumed to be invariant; however, small OR variations may cause significant shifts in the calculated size of the terrestrial biospheric C sink [ Randerson, et al., 2006]. Accurate measurements of OR are necessary for the accurate apportionment of fossil fuel CO₂ between the atmosphere, oceans, and terrestrial biosphere. Ecosystem OR is linearly related to C_ox, a parameter which can be easily measured via elemental analysis, calorimetry, or solid state nuclear magnetic resonance [ Masiello, et al., 2007]. We are measuring C_ox and OR at the three deciduous forest sites within the Kellogg Biological Station NSF LTER (lter.kbs.msu.edu). We report OR from litter collected from three forest sites from 1998-2003, a time series which covers periods of both normal and low precipitation. We also report error introduced in the C_ox to OR conversion via a range of plausible assumptions about ecosystem N cycling. Keeling, R. F., et al. (1996), Global and hemispheric CO₂ sinks deduced from changes in atmospheric O₂ concentration, Nature, 381, 218-221. Masiello, C.A. et al. (in review 2007) Two new approaches for measuring ecosystem carbon oxidation state and oxidative ratio. J.G.R. Biogeosciences. Randerson, J. T., et al. (2006), Is carbon within the global terrestrial biosphere becoming more oxidized? Implications for trends in atmospheric O₂, Global Change Biology, 12, 260-271.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 3355 Regional modeling
SC: Biogeosciences [B]
MN: 2007 Fall Meeting